Measuring small artery resistance in pulmonary hypertension

Impact of the Pulmonary Index of Microcirculatory Resistance in Pulmonary Arterial Hypertension

University of California, Los Angeles · NCT05812976

This study is testing a new way to measure how well small arteries are working in people with pulmonary arterial hypertension to see if it can help doctors understand the condition better and track changes after starting treatment.

Quick facts

Study typeObservational
Enrollment50 (estimated)
Ages18 Years and up
SexAll
SponsorUniversity of California, Los Angeles (other)
Locations1 site (Los Angeles, California)
Trial IDNCT05812976 on ClinicalTrials.gov

What this trial studies

This observational study aims to measure the resistance of small arteries in patients with pulmonary arterial hypertension (PAH) using a novel index called the Pulmonary Index of Microcirculatory Resistance (PIMR). The measurements will be taken during standard cardiac catheterizations, allowing researchers to correlate these new indices with traditional metrics used to assess the severity of PAH. Additionally, the study will evaluate changes in these indices among newly diagnosed patients six months after initiating treatment. The goal is to enhance understanding of pulmonary vascular resistance and improve prognostic capabilities in PAH.

Who should consider this trial

Good fit: Ideal candidates for this study are individuals diagnosed with Group 1 pulmonary arterial hypertension who meet specific hemodynamic criteria.

Not a fit: Patients with other forms of pulmonary hypertension or those contraindicated for fluoroscopy and coronary angiography may not benefit from this study.

Why it matters

Potential benefit: If successful, this study could lead to improved diagnostic and prognostic tools for patients with pulmonary arterial hypertension.

How similar studies have performed: While this approach is novel in the context of pulmonary hypertension, similar methodologies have shown promise in other cardiovascular conditions.

Eligibility criteria

Show full inclusion / exclusion criteria
Inclusion Criteria:

* Diagnosis of Group 1 PAH with invasive pulmonary hypertension defined as: Mean pulmonary arterial pressure ≥ 20 mmHg, pulmonary capillary wedge pressure \< 15 mmHg, and pulmonary vascular resistance ≥ 3 Wood units.
* Serum creatinine \< 2.0 mg/dL
* Able to provide informed written consent

Exclusion Criteria:

* Other groups/forms of pulmonary hypertension (i.e. groups 2-5)
* Contraindicated to undergo fluoroscopy and/or coronary angiography
* Pregnancy

Where this trial is running

Los Angeles, California

Study contacts

How to participate

  1. Review the eligibility criteria above with your treating physician.
  2. Visit the official trial page on ClinicalTrials.gov for the most current contact information and recruitment status.
  3. Contact the listed study coordinator or principal investigator to request pre-screening. Pre-screening is free and never obligates you to enroll.

View on ClinicalTrials.gov →

Conditions: Pulmonary Hypertension, Pulmonary Index of Microcirculatory Resistance, Pulmonary Arterial Hypertension, Index of Microcirculatory Resistance

Last reviewed 2026-05-15 by the Find a Trial editorial team. Information on this page is for educational purposes and is not medical advice. Always consult qualified healthcare professionals about clinical trial participation.